BRPI0809638B1 - PREPREGNATED COMPOSITE MATERIAL UNDERSTANDING MULTIFUNCTIONAL AROMATIC EPOXY RESIN AND ITS PRODUCTION METHOD - Google Patents

Abstract

Pre- impregnated composite material (prepreg) is provided that can be molded to form composite parts that have high levels of both strength and damage tolerance without causing any substantial negative impact upon the physical or chemical characteristics of the uncured prepreg or cured part. This is achieved by including in the matrix resin a substantial amount of a multifunctional aromatic epoxy resin that has at least one phenyl group that is meta-substituted.

Description

(54) Title: PRE-IMPREGNATED COMPOSITE MATERIAL UNDERSTANDING MULTIFUNCTIONAL AROMATIC EPOXY RESIN AND ITS PRODUCTION METHOD (51) Int.CI .: C08G 59/38; C08G 59/40; C08G 59/50; C08J 5/24; C08L 63/00; C08L 77/00; C08L 81/06 (30) Unionist Priority: 4/17/2007 US 11 / 787,700 (73) Holder (s): HEXCEL CORPORATION (72) Inventor (s): DAVID TÍLBROOK; DANA BLAIR; MAUREEN BOYLE; PAUL MACKENZIE

1/28 “PRE-IMPREGNATED COMPOSITE MATERIAL UNDERSTANDING

MULTIFUNCTIONAL AROMATIC EPOXY RESIN AND ITS METHOD OF

PRODUCTION"

BACKGROUND OF THE INVENTION

1. Field of the Invention [001] The present invention is generally related to prepreg composite material (prepreg) which is used in the production of high performance composite parts. More particularly, the invention is directed to providing prepreg that can be cured / molded to form composite parts having both improved strength and damage tolerance.

2. Description of the Related Art [002] Composite materials are typically composed of a continuous resinous matrix and reinforcement fibers as the two primary constituents. Composite materials are often required to perform in demanding environments, such as aerospace, and therefore the limits and physical characteristics of the composite are of crucial importance. In particular, when determining how light certain parts of composite material can be, tensile strength and its modulus are important factors.

[003] The prepreg composite material (prepreg) is used widely in the manufacture of composite parts. Prepreg is a combination of an uncured resin matrix and fibrous reinforcement, which is in a form that is ready for molding and curing in the form of the final composite part. By pre-impregnating the fibrous reinforcement with resin, the manufacturer can carefully control the amount and placement of the resin that is impregnated within the fibrous mesh and ensure that the resin is distributed in the mesh as desired. It is well known that the relative amount of fibers and resin in a composite part and the distribution of the resin within the fibrous mesh have a great effect on the structural properties of the part. Prepreg is a preferred material for use in the manufacture of load-bearing structural parts, particularly composite parts for

Petition 870180031805, of 04/19/2018, p. 10/42

2/28 use in the aerospace industry. It is important that these parts have sufficient strength, damage tolerance and other requirements that are routinely established for such parts.

[004] The fibrous reinforcements that are commonly used in prepreg for use in the aerospace industry are multidirectional woven structural wefts or unidirectional tapes that contain fibers extending parallel to each other. The fibers are typically in the form of bundles of numerous individual fibers which are referred to as "tow". The fibers or tow can also be perforated and randomly oriented in the resin to form a non-woven mat. These various fibrous reinforcement configurations are impregnated with a carefully controlled amount of uncured resin. The resulting prepreg is typically placed between protective layers and rolled up for storage or transport to the manufacturing plant.

[005] The prepreg can also be in the form of short segments of perforated unidirectional tape that are randomly oriented to form a non-woven mat of perforated unidirectional tape. This type of prepreg is referred to as an “almost-isotropic perforated prepreg”. Perforated quasi-isotropic prepreg is similar to the traditional non-woven fibrous mat prepreg, except that the short lengths of the unidirectional perforated tape (splinters) are randomly oriented on the mat rather than the perforated fibers.

[006] The tensile strength of a cured composite material is largely dictated by the individual properties of the reinforcing fiber and resinous matrix, as well as the interaction between these two components. Additionally, the fiber-resin volumetric ratio is an important factor. Cured composites that are stressed tend to fail through a mechanism of accumulated damage that arises from multiple stress breaks in the individual fiber filaments in the reinforcement tow. Once the stress levels in the resin adjacent to the ends of the broken filament become too great, the composite as a whole fails. Therefore, the fiber strength, the matrix strength, and the dissipation efficiency of tenPetição 870180031805, of 04/19/2018, p. 11/42

3/28 sections in the vicinity of the ends of the broken filament will contribute to the tensile strength of a cured composite material.

[007] In many applications, it is desirable to maximize the tensile strength property of the cured composite material. However, attempts to maximize tensile strength can often result in negative effects on other desirable properties, such as the compression performance and damage tolerance of the composite structure. Additionally, attempts to maximize tensile strength can have unpredictable effects on the prepreg's grip or survival. The tackiness or adherence of the uncured prepreg is commonly referred to as "tack". The grip of the uncured prepreg is an important consideration during layering and molding operations. Prepreg with little or no handle is difficult to transform into laminates that can be shaped to form structurally strong composite parts. Conversely, the prepreg with a lot of handle can be difficult to handle and also difficult to place inside the mold. It is desirable that the prepreg has the right amount of handle to ensure easy handling and good laminate / molding characteristics. In any attempt to increase the resistance and / or damage tolerance of a given cured composite material, it is important that the handle of the uncured prepreg remains within acceptable limits to ensure proper handling and molding of the prepreg.

[008] The “survival” of the prepreg is the period of temperature that the prepreg can be exposed to environmental conditions before experiencing an unacceptable degree of cure. Survival can vary widely depending on a variety of factors, but it is mainly controlled by the formulation of the resin being used. The survival of the prepreg must be long enough to allow normal handling, layering and molding operations to be achieved without the prepreg experiencing unacceptable levels of cure. In any attempt to increase the resistance and / or damage tolerance of a given cured composite material, it is important that the survival of the uncured prepreg remains as long as possible to allow sufficient time for the PROPETITION 870180031805, of 19/04/2018, p. 12/42

4/28 cessation, handling and disposition of the prepreg layers before curing.

[009] The most common method of increasing the tensile performance of the composite is to change the fiber surface in order to weaken the bond strength between the matrix and the fiber. This can be achieved by reducing the amount of electro-oxidant treatment of the fiber surface after graphitization. The reduction of the bond strength of the fiber in the matrix introduces a mechanism for the dissipation of the stresses at the exposed ends of the filament through the interfacial detachment. This interfacial detachment provides an increase in the amount of traction damage that a composite part can withstand before failing with tension.

[010] Alternatively, the application of a coating or “sealing agent” to the fiber may lower the resin-fiber bond. This approach is well known in fiberglass composites, but it can also be applied to composites reinforced with carbon fibers. Using these strategies, it is possible to achieve significant increases in tensile strength. However, the improvements are accompanied by a reduction in properties, such as resistance to post-impact compression (CAI), which requires high bond strength between the resin matrix and the fibers.

[011] Another alternative approach is to use a lower modulus matrix. A lower modulus resin reduces the level of stress that accumulates in the immediate vicinity of broken filaments. This is usually accomplished either by selecting resins with intrinsically lower modulus (eg cyanate esters), or by incorporating an ingredient such as an elastomer (carbadoxy-terminated butadiene-acrylonitrile [CTBN], amino-terminated butadiene-acrylonitrile [ATBN ] and the like). Combinations of these diverse approaches are also known.

[012] The selection of lower module resins can be effective in increasing the tensile strength of the composite. However, this can result in a tendency to damage tolerance, which is typically measured by a reduction in proPetition 870180031805, of 4/19/2018, p. 13/42

5/28 compressive properties, lime as post impact impact resistance (CAI) and naked hole compression resistance (OHC). It is therefore very difficult to achieve a simultaneous increase in both tensile strength and damage tolerance.

[013] While existing prepregs are well suited for their intended use in providing composite parts that are strong and tolerant of damage, there is still a continuing need to provide prepregs that can be used to produce composite parts that have even higher levels of both. resistance and damage tolerance. However, this increase in resistance and damage tolerance needs to be achieved without negatively influencing the prepreg's grip and survival, as well as the other physical properties of the cured composite structure.

SUMMARY OF THE INVENTION [014] According to the present invention, pre-impregnated composite material (prepreg) is provided which can be molded to form composite parts that have high levels of both resistance and damage tolerance. This is achieved without causing any substantially negative impact on the physical or chemical properties of the uncured prepreg or the cured composite part.

[015] The pre-impregnated composite materials of the present invention are composed of reinforcing fibers and a matrix. The matrix includes a difunctional epoxy resin in combination with a multifunctional aromatic epoxy resin with a functionality greater than two in which the multifunctional aromatic epoxy resin has at least one phenyl group that is meta-substituted. The matrix additionally includes thermoplastic particles, a thermoplastic curing agent and a curing agent.

[016] The present invention also encompasses methods for producing the prepreg and methods for molding the prepreg in the form of a wide variety of composite parts. The invention also encompasses the composite parts that are produced petition 870180031805, of 04/19/2018, p. 14/42

6/28 das using the improved prepreg.

[017] It has been discovered that the selection and combination of the components of the present invention results in the formation of a prepreg that can be molded to form composite parts that have both improved tensile strength and post-impact compression strength (CAI) compared to conventional systems.

[018] Additionally, it has been unexpectedly discovered that the benefits of improved tensile strength and CAI strength can be obtained without substantially influencing other desired physical properties of the prepreg (eg, grip and survival) or the resulting cured composite material (eg, bonding fiber matrix, damage tolerance, stress dissipation, compression performance and the like).

[019] The features described above and many other intended features and advantages of the present invention will be better understood by reference to the detailed description presented below.

DETAILED DESCRIPTION OF THE INVENTION [020] The pre-impregnated composite materials (prepreg) of the present invention can be used as a replacement for the existing prepreg being used to form composite parts in the aerospace industry and in any other application where high strength structural and damage tolerance is required. The invention involves replacing the resin formulations of the present invention in place of the existing resins being used to produce the prepreg. Accordingly, the resin formulations of the present invention are suitable for use in any of the conventional prepreg manufacturing and curing processes.

[021] The pre-impregnated composite materials of the present invention are, like all conventional prepregs, composed of reinforcing fibers and an uncured matrix. Reinforcement fibers can have any of the conventional fiber configurations that are used in the prepreg industry. However, the matrix

Petition 870180031805, of 04/19/2018, p. 15/42

7/28 departs from the conventional practice of the prepreg industry. Specifically, the matrix includes a difunctional epoxy resin in combination with a multifunctional aromatic epoxy resin with a functionality greater than two in which the multifunctional aromatic epoxy resin has at least one phenyl group that is meta-substituted. The matrix additionally includes thermoplastic particles, a thermoplastic curing agent and a curing agent.

[022] It has been discovered that the use of an epoxy resin with a functionality greater than two having at least one meta-substituted phenyl ring in its main chain in place of the para-substituted glycidyl amine resins, which are conventionally used in the production matrices of prepreg for the aerospace industry, give the composite material greater toughness, as well as increasing the modulus of the base resin. This gives rise to a stage of change in the performance of post-impact compression (CAI). Surprisingly, the matrix resins of the present invention also impart a very high tensile strength (e.g. bare hole tensile strength - OHT) to the composite material.

[023] The difunctional epoxy resin used to form the matrix can be any suitable difunctional epoxy resin. It will be understood that this includes any suitable epoxy resins having two epoxy functional groups. The difunctional epoxy resin can be saturated, unsaturated, cycloaliphatic, alicyclic or heterocyclic.

[024] Difunctional epoxy resins, for example, include those based on: Bisphenol F diglycidyl ether, Bisphenol A (optionally brominated), phenol and cresol epoxy novolacs, glycidyl phenol-aldehyde adduct ethers, glycidyl diol ethers, diglycidyl ether, diglycidyl diethylene glycol ether, Epikote, Epon, aromatic epoxy resins, polyglycidyl aliphatic ethers, epoxidated olefins, brominated resins, aromatic glycidyl amines, glycidyl imidines and heterocyclic amides, any of these glycidylated or hydroxy etheric compounds. The difunctional epoxy resin is preferably selected from diglycidyl ether of bisphenol F, diglycidyl ether from bisphenol A, diglycidyl dihydroxy naphthalene, or any combination thereof. Most preferred is ether

Petition 870180031805, of 04/19/2018, p. 16/42

8/28 diglycidyl bisphenol F. Diglycidyl ether bisphenol F is commercially available from Huntsman Advanced Materials (Brewster, NY) under the trade names of

Araldite GY281 and GY285. The difunctional epoxy resin can be used alone or in any suitable combination.

[025] The difunctional epoxy resin is present in the range of 10% w to 40% w of the resin matrix. Preferably, the difunctional epoxy resin is present in the range of 15% w to 35% w. More preferably, the difunctional epoxy resin is present in the range of 22% w to 28% w.

[026] The second component of the matrix is an epoxy resin with a functionality greater than two that has at least one meta-substituted phenyl ring in its main chain. It will be understood that this includes epoxy resins having an epoxy group functionality greater than two. Preferred multifunctional epoxy resins are those that are trifunctional or tetrafunctional. Most preferably, the multifunctional epoxy resin is tri-functional.

[027] A trifunctional epoxy resin will be understood to have the three epoxy groups substituted either directly or indirectly in a meta-orientation on the phenyl ring in the main chain of the compound. A tetrafunctional epoxy resin will be understood to have the four epoxy groups substituted either directly or indirectly in a meta-orientation on the phenyl ring in the main chain of the compound.

[028] It is also envisioned that the phenyl ring may be optionally substituted with other suitable non-epoxy substituent groups. Suitable substituent groups include, by way of example, hydrogen, hydroxyl radicals, alkyl, alkenyl, alkynyl, alkoxy, aryl, aryloxy, aralkyloxy, aralkyl, halo, nitro or cyano. Suitable non-epoxy substituent groups can be attached to the phenyl ring in the para or ortho positions, or linked in a meta position not occupied by an epoxy group. Suitable tetrafunctional epoxy resins include N, N, N ', N'-tetraglycidyl-mxylenediamine (commercially available from Mitsubishi Gas Chemical Company (New York, New York) under the trade name Tetrad-X), and Erisys GA-240 (from CVC

Petition 870180031805, of 04/19/2018, p. 17/42

9/28

Chemicals, Moorestown, New Jersey). Suitable trifunctional epoxy resins include, by way of example, those based on Bisphenol F, Bisphenol A (optionally brominated), phenol and cresol epoxy novolacs, glycidyl ethers of phenol-aldehyde adductors, aromatic epoxy resins, triglycidic diallytic ethers, polyglycidyl ethers, poly aliphatic ethers epoxidated olefins, brominated resins, aromatic glycidyl amines, glycidyl imidines and heterocyclic amides, glycidyl ethers, fluorinated epoxy resins, or any combination thereof.

[029] A preferred trifunctional epoxy resin is triglycidyl meta-aminophenol. Triglycidyl meta-aminophenol is commercially available from Huntsman Advanced Materials under the trade name Araldite MY0600, and from Sumitomo Chemical Co. (Osaka, Japan) under the trade name ELM-120.

[030] The epoxy resin with a functionality greater than two having at least one meta-substituted phenyl ring in its main chain is present in the range of 15% w to 45% w of the resin matrix. Preferably, the meta-substituted epoxy resin is present in the range of 20% w to 40% w. Most preferred are matrix resins in which the meta-substituted epoxy multifunctional is present in the range of 25% w to 30% w.

[031] The resin matrix may include one or more multifunctional epoxy resins in addition to the required meta-substituted multifunctional epoxy resin. Additional epoxy resins are those that have an epoxy functionality of at least three, and that do not have a phenyl ring in their main chains that is meta-substituted with an epoxy group. Additional optional multifunctional epoxy resins can be saturated, unsaturated, cycloaliphatic, alicyclic or heterocyclic.

[032] Suitable additional multifunctional epoxy resins include, by way of example, those based on ethers of glycidyl phenol-aldehyde adductors, aromatic epoxy resins, triglycidyl dialiphatic ethers, polyglycidyl aliphatic ethers, epoxidized olefins, brominated amine, glycidyl amine, glycidyl amine, glycidyl amine and heterocyclic amides, glycidyl ethers, fluorinated epoxy resins, or any other competition 870180031805, of 04/19/2018, p. 18/42

10/28 combination of those mentioned.

[033] Specific examples of suitable additional multifunctional epoxy resin include, by way of example, N, N, N ', N'-tetraglycidyl-4,4'-diaminodiphenyl methane (TGDDM commercially available as Araldite MY720 and MY721 from Huntsman Advanced Materials , or ELM 434 from Sumitomo), triglycidyl para-aminophenol ether (commercially available as Araldite MY 0500 or MY 0510 from Huntsman Advanced Materials), dicyclopentadiene based epoxy resins such as Tactix 556 (commercially available from Huntsman Advanced Materials), tris- (phenyl hydroxyl), and methane-based epoxy resin such as Tactix 742 (commercially available from Huntsman Advanced Materials). Other suitable multifunctional epoxy resins include DEN 438 (from Dow Chemicals, Midland, MI), DEN 439 (from Dow Chemicals), Araldite ECN 1273 (from Huntsman Advanced Materials), and Araldite ECN 1299 (from Huntsman Advanced Materials).

[034] The additional multifunctional epoxy resins can be used alone or in any suitable combination. The additional multifunctional epoxy resin (s), if present, should be in the range of 0.1% w to 20% w of the resin matrix. Preferably, the multifunctional epoxy resin (s) is (are) present in the range of 1% w to 15% w. More preferably, the multifunctional epoxy resin (s) is (are) present in the range of 5% w to 10% w.

[035] The prepreg matrix according to the present invention also includes insoluble particles of thermoplastics. The term insoluble thermoplastic particles' as used herein means any suitable material that is thermoplastic and in a powder form, atomized form, or particle form and that remains substantially in particulate form in the prepreg resin matrix prior to curing. Insoluble particles of thermoplastics may experience some melting when the matrix temperature is increased during curing. However, the particles substantially reform and remain in particulate form in the final cured matrix.

[036] Insoluble thermoplastic particles are polymers, which can

Petition 870180031805, of 04/19/2018, p. 19/42

11/28 be in the form of homopolymers, block copolymers, graft copolymers, or terpolymers. The insoluble particles of thermoplastics can be thermoplastic resins having single or multiple bonds selected from carbonocarbon bonds, carbon-oxygen bonds, silicon-oxygen bonds and carbon-sulfur bonds. One or more repeating units may be present in the polymer which incorporates the following fractions within one or the other of the main polymer chain or pendant side chains of the main polymer chain: amide fractions, imide fractions, ester fractions, ether fractions, carbonate fractions, urethane fractions, thioether fractions and carbonyl fractions. The thermoplastic may also have a partially cross-linked structure. It can be either crystalline or amorphous or partially crystalline.

[037] Suitable examples of insoluble thermoplastic particles include, by way of example, polyamides, polycarbonates, polyacetal, polyphenylene oxides, polyphenylene sulfides, polyarylates, polyethers, polyesters, polyimides, polyamidoimides, imide polyethers, polyether and polyether and polyether. .

[038] Insoluble thermoplastic particles can be chosen, for example, from polyamide 6 (caprolactam - PA6), polyamide 12 (laurolactam - PA 12), polyamide 11 or any combination of these mentioned. Preferred insoluble particles of thermoplastics are polyamide particles that have a melting point between about 150 ° C and 250 ° C. The particles must have particle sizes below 100 microns. It is preferred that the average particle size is around 20 microns. Suitable polyamide particles are commercially available from France's Arkema, under the trade name Orgasol.

[039] Insoluble particles of thermoplastics are present in the range of 35% w to 1% w of the matrix. Preferably, insoluble thermoplastic particles are present in the range of 20% w to 5% w. More preferably, insoluble thermoplastic particles are present in the range of 20% w to 10% w. Most preferably, insoluble thermoplastic particles are present in the range of 10% w to 15% w of the matrix.

Petition 870180031805, of 04/19/2018, p. 20/42

12/28 [040] In order to achieve further improvements in damage tolerance (CAI) and bare hole tensile strength, it is preferred that at least part of the insoluble particles of thermoplastics, which are preferably polyamide particles, have melts that are below the curing temperature of the prepreg (typically 180 ° C) and that such low melting particles are used alone or in combination with higher melting polyamide particles.

[041] Polyamide particles arrive in a variety of degrees that have different melting temperatures depending on the particular polyamide, degree of copolymerization and polymerization and degree of crystallinity. Particles containing polyamide 6 (P A6) typically have melting points above typical prepreg curing temperatures. Therefore, little or no dissolution of the PA6 particles occurs during curing. The NAT1 Orgasol 1002 D (100% PA6) with a melting point of 217 ⁰ C (DSC) and particle size of 20 microns is an example of polyamide particles such high melting point. On the other hand, polyamide 12 (PA 12) particles and copolymers of PA6 and PA 12 have melting temperatures that are generally below the typical curing temperature for epoxy prepregs. These types of low melting particles experience substantially melting at curing temperatures and are reformed into particles as the cured composite is cooled.

[042] Preferred particles are polyamide PA6 particles and particles which are copolymers of PA6 and PA 12. For example Orgasol 3502 D NAT 1 is a copolymer of 50% PA12 and 50% PA 6 having a melting point of 142 ⁰ C with average particle size that varies around 20 microns. As a further example, Orgasol CG 199 degree growth is a copolymer of 80% PA 12 and 20% PA6 having a melting point of 160 ⁰ C with an average particle size ranging from about 20 microns. As another example, Orgasol 3801 DNAT1 is a copolymer of PA 12 and PA6 that has a melting point of 160 ° C, particle size 20 microns and a molecular weight greater than CG199. The molecular weight of Orgasol 3801

Petition 870180031805, of 04/19/2018, p. 21/42

13/28

DNAT1 is comparable to Orgasol 1002 DNAT1. Orgasol CG213 is another preferred copolymer particle that contains 80% PA 12 and 20% PA6, has a melting point of 160 ° C, particle sizes around 20 microns and a higher molecular weight than Orgasol CG199. The use of Orgasol CG 199 or CG213 by themselves is not preferred due to a reduction in CAI despite the increase in OHT. It is therefore preferred that Orgasol CG199 or CG213 is combined with polyamide particles of higher melting points.

[043] The above identified polyamide homopolymer and copolymer particles can be included in the matrix alone or in combination. However, it is preferred that a mixture of polyamide particles is used which includes a high melting point polyamide component (ie melting temperature above the curing temperature for the prepreg) and a low melting point polyamide component (ie temperature melting temperature below the curing temperature for the prepreg). However, the relative amounts of high and low melting point particles can be varied, if desired. It was discovered that by using at least part of low melting polyamide particles (copolymer of PA6 and PA 12), it is possible to obtain low modulus intercalation without influencing the base resin modulus, and additionally without compromising full water resistance of the composite under wet conditions in relation to the effects of moisture.

[044] The prepreg matrix resin includes at least one curing agent. Suitable curing agents are those which facilitate the curing of the epoxy-functional compounds of the invention and, in particular, facilitate the polymerization by opening the ring of such epoxy compounds. In a particularly preferred embodiment, such curing agents include those compounds which polymerize with the compound or epoxy-functional compounds, in their polymerization by ring opening. Two or more of such curing agents can be used in combination.

[045] Suitable curing agents include anhydrides, particularly polycarboxylic anhydrides, such as naic anhydride (NA), methylnadic anhydride (MNA available from Aldrich), phthalic anhydride, tetrahydrophthalic anhydride, anhydride

Petition 870180031805, of 04/19/2018, p. 22/42

14/28 hexahydrophthalic (HHPA - available from Anhydrides and Chemicals Inc., Newark, NJ.), Methyltetrahydrophthalic anhydride (MTHPA - available from Anhydrides and Chemicals Inc.), methylexahydrophthalic anhydride (MHHPA - available from Anhydrides and Chemicals Inc.), anhydride endomethylenetetrahydrophthalic, hexachloroendomethylenetetrahydrophthalic anhydride (Chlorentric Anhydride - available from Velsicol Chemical Corporation, Rosemont, 111.), trimethyl anhydride, pyromethyl dianhydride, maleic anhydride (MA - available from Aldrich), succinic anhydride (anhydrous) available from Anhydrides and Chemicals Inc.), polysebacterial polyanhydride, and polyzealic anhydride.

[046] Suitable additional curing agents are amines, including aromatic amines, for example, 1,3-diaminobenzene, 1,4-diaminobenzene, 4,4'-diaminodiphenylmethane, and polyaminesulfones, such as 4,4'-diaminodiphenyl sulfone (4,4'-DDS - available from Huntsman), 4-aminophenyl sulfone, and 3,3'-diaminodiphenyl sulfone (3,3'-DDS).

[047] Also, suitable curing agents can include polyols, such as ethylene glycol (EG - available from Aldrich), poly (propylene glycol), and (poly) vinyl alcohol; and phenol-formaldehyde resins, such as phenol-formaldehyde resin having an average molecular weight of about 550-650, pt-butylphenol-formaldehyde resin having an average molecular weight of about 600-700, and pn resin -octylphenolformaldehyde, having an average molecular weight of about 1200-1400, these being available as HRJ 2210, HRJ-2255, and SP-1068, respectively, from Schenectady Chemicals, Inc., Schenectady, NY). In addition to phenolformaldehyde resins, a combination of CTU guanamine, and phenol-formaldehyde resin having a molecular weight of 398 (commercially available as CG-125 from Ajinomoto USA Inc. (Teaneck, NJ.)), Is also suitable.

[048] Different commercially available compositions can be used as curing agents in the present invention. One such composition is AH-154, a diciandiamide type formulation, available from Ajinomoto USA Inc. Others that are suitable include Ancamide 400, which is a mixture of polyamide, diethyltriamine, and

Petition 870180031805, of 04/19/2018, p. 23/42

15/28 triethylenetetraamine, Ancamide 506, which is a mixture of amidoamine, imidazoline, and tetraethylenepentaamine, and Ancamide 1284, which is a mixture of 4,4'methylenediamine and 1,3-benzenediamine; these formulations are available from

Pacific Anchor Chemical, Performance Chemical Division, Air Products and Chemicals,

Inc., Allentown, Pa.

[049] Additional suitable curing agents include imidazole (1,3-diaza-2,4cyclopentadiene) available from Sigma Aldrich (St. Louis, Missouri), 2-ethyl-4methylimidazole available from Sigma Aldrich, and boron trifluoride amine complexes , such as Anchor 1170, available from Air Products & Chemicals, Inc.

[050] Still additional suitable curing agents include 3,9-bis (3 aminopropyl-2,4,8,10- tetroxaspiro [5.5] undecane, which is commercially available as ATU, from Ajinomoto USA Inc., as well as aliphatic dihydrazide, which is commercially available as Ajicure UDH, also from Ajinomoto USA Inc., and mercapto-terminated polysulfide, which is commercially available as LP540, from Morton International, Inc., Chicago, 111.

[051] Curing agents are selected such that they provide the curing of the resin component of the composite material when combined with them at appropriate temperatures. The amount of curing agent required to provide adequate curing of the resin component will vary depending on a number of factors including the type of resin being cured, the desired curing temperature and curing time. Curing agents typically include cyanoguanidine, aromatic and aliphatic amines, acid anhydrides, Lewis acids, substituted ureas, imidazoles and hydrazines. The particular amount of curing agent required for each particular situation can be determined through well-known routine experimentation.

[052] Preferred representative curing agents include 4,4'-diaminodiphenyl sulfone (4,4'-DDS) and 3,3'-diaminodiphenyl sulfone (3,3'-DDS), both commercially available from Huntsman. The curing agent is present in an amount ranging from 45% w to 5% w of the uncured matrix. Preferably, the

Petition 870180031805, of 04/19/2018, p. 24/42

16/28 cure is present in an amount ranging from 30% w to 10% w. More preferably, the curing agent is present in the range of 25% w to 15% w of the uncured matrix. Most preferred are matrix resins that contain from 16% w to 22% w of curing agent.

[053] 4,4'-DDS is a preferred curing agent. It is preferably used as the only curing agent in amounts ranging from 16% w to 33% w. It was found that the more reactive 3,3'-DDS provided increased resistance in the cured pure resins, but that the resulting prepregs had grip properties that were not close to being considered good as those using the less reactive 4,4'-DDS. Therefore, in order to achieve the optimum balance of prepreg survival, the grip and mechanical performance of the cured composite part, it is preferred that less reactive curing agents, such as 4,4'-DDS and the like, are used in an amine stoichiometry for epoxy of about 70 to 80 percent.

[054] The matrix of the present invention also preferably includes a thermoplastic curing agent. Any suitable thermoplastic polymers can be used as the curing agent. Typically, the thermoplastic polymer is added to the resin mixture as particles that are dissolved in the resin mixture by heating prior to the addition of the curing agent. Once the thermoplastic agent is substantially dissolved in the hot resin matrix precursor (i.e. the epoxy resin mixture), the precursor is cooled and the remaining ingredients (curing agent and insoluble thermoplastic particles) are added.

[055] Representative thermoplastic curing agents / particles include any of the following thermoplastics, either alone or in combination: polyimides, aramides, polyketones, polyetheretherketones, polyesters, polyurethanes, polysulfones, polyethersulfones, high performance hydrocarbon polymers, liquid crystalline polymers, PTFE, elastomers, and segmented elastomers.

[056] The hardening agent is present in the range of 45% w to 5% w of

Petition 870180031805, of 04/19/2018, p. 25/42

17/28 uncured resinous matrix. Preferably, the curing agent is present in the range of 25% w to 5% w. More preferably, the curing agent is present in the range of 20% w to 10% w. Most preferably, the curing agent is present in the range of 13% w to 17% w of the resin matrix. A suitable hardening agent, for example, consists of PES particles marketed under the trade name Sumikaexcel 5003P, which is commercially available from Sumitomo Chemicals. Alternatives to 5003P are polyethersulfone 105PS Solvay, polyethersulfone 105PS, or finished non-hydroxyl grades such as Solvay 104P.

[057] The resinous matrix may also include additional ingredients, such as performance enhancing or modifying agents and additional thermoplastic polymers as long as they do not negatively influence the grip and survival of the prepreg or the resistance and damage tolerance of the cured composite part. Performance enhancing or modifying agents, for example, can be selected from flexibilizers, curing agents / particles, accelerators, core layer elastomers, flame retardants, wetting agents, pigments / dyes, UV absorbers, antifungal compounds , fillers, conductive particles, and viscosity modifiers. Additional thermoplastic polymers suitable for use as additional curing agents include any of the following, either alone or in combination: polyether sulfones (PES), polyether ethers (PEES), polyphenyl sulfones, polysulfones, polyimides, polyetherimide, aramid, polyesters, polyketones, polyetheretherketones (PEEK), polyurethane, polyureas, polyaryl ether, polyaryl sulfides, polycarbonates, polyphenylene oxides (PPO) and modified PPO.

[058] Suitable accelerators are any of the urone compounds that are commonly used. Specific examples of accelerators, which can be used alone or in combination, include N, N-dimethyl, N'-3,4-dichlorphenyl urea (Diuron),

N'-3-chlorophenyl urea (Monuron), and preferably N, N- (4-methyl-m-phenylene bis [N ', N'dimethylurea] (Dyhard UR500 from Degussa or UR2T from CVC Chemicals).

Petition 870180031805, of 04/19/2018, p. 26/42

18/28 [059] Suitable fillers include, by way of example, any of the following or alone or in combination: silicas, aluminas, titania, glass, calcium carbonate and calcium oxide.

[060] Suitable conductive particles include, by way of example, any of the following or alone or in combination: silver, gold, copper, aluminum, nickel, degrees of conductive carbon, buckminsterfulerene, carbon nanotubes, and carbon nanofibers. Metal-coated fillers can also be used, for example, nickel-coated carbon particles and silver or copper-coated silica particles.

[061] The resinous matrix may comprise an additional polymeric resin that is at least a thermoset resin. The term "thermosetting resin" includes any suitable material that is plastic and usually liquid, powder, or malleable prior to curing and designed to be molded into a final shape. Once cured, a thermoset resin is not suitable for melting or remolding. Suitable thermosetting resinous materials for the present invention include, but are not limited to, phenolformaldehyde, urea-formaldehyde, 1,3,5-triazin-2,4,6-triamine (Melamine) resins, bismaleimide, vinyl ester resins, resins benzoxazine, phenolic resins, polyesters, cyanate ester resins, epoxide polymers, or any combination thereof. The thermosetting resin is preferably selected from epoxide resins, cyanate ester resins, bismaleimide, vinyl ester, benzoxazine and phenolic resins. If desired, the matrix can include additional suitable resins containing phenolic groups, such as resorcinol based resins, and resins formed by cationic polymerization, such as DCPD - phenol copolymers. Additional suitable resins are melamine-formaldehyde resins and urea-formaldehyde resins.

[062] The resin matrix is produced according to the standard prepreg matrix procedure. In general, the various epoxy resins are mixed together at room temperature to form a resinous mixture to which the thermoplastic hardening agent is added. This mixture is then heated to a temperature above the melting point of the thermoplastic curing agent by

Petition 870180031805, of 04/19/2018, p. 27/42

19/28 a sufficient period of time to substantially melt the curing agent. The mixture is then cooled to room temperature or below and the rest of the ingredients (insoluble particles of thermoplastics, curing agent and other additives, if any) are mixed in the resin to form the final resin matrix that is impregnated in the fibrous reinforcement.

[063] The resinous matrix is applied to the fibrous reinforcement according to any of the known prepreg preparation techniques. The fibrous reinforcement can be totally or partially impregnated with the resin matrix. In an alternative embodiment, the resinous matrix can be applied to the fibrous reinforcement as a separate layer, which is nearby, and in contact with the fibrous reinforcement, but does not substantially impregnate the fibrous reinforcement. The prepreg is typically covered on both sides with a protective film and rolled up for storage and transportation at temperatures that are typically kept well below room temperature to prevent premature curing. Any of the other prepreg manufacturing processes and storage / transport systems can be used if desired.

[064] The fibrous reinforcement of the prepreg can be selected from hybrid or mixed fibrous systems that comprise synthetic or natural fibers, or a combination of these. The fibrous reinforcement can preferably be selected from any suitable material such as fiberglass, carbon fibers or aramid (aromatic polyamide). The fibrous reinforcement is preferably made of carbon fibers.

[065] The fibrous reinforcement can comprise fractured fibers (that is, broken by stretching) or selectively discontinuous fibers, or continuous fibers. It is envisioned that the use of fractured or selectively staple fibers can facilitate layering of the composite material before it is completely cured, and improves its ability to be molded. The fibrous reinforcement may be in a woven, non-corrugated, non-woven, unidirectional or multiaxial textile structural form, such as perforated quasi-isotopic prepreg. The woven shape can be selected from a flat, smooth, or diagonal weave style. Non-wavy and multiaxial shapes

Petition 870180031805, of 04/19/2018, p. 28/42

20/28 can have a number of thickness measurements and fiber orientations. Such styles and shapes are well known in the field of composite reinforcement, and are commercially available from several companies, including Hexcel Reinforcements of Villeurbanne, France.

[066] The prepreg can be in the form of continuous tapes, tow, fabrics or perforated lengths (perforation or cracking operations can be performed at any time after impregnation). The prepreg can be an adhesive or superficial film and can additionally have carriers in various forms, both woven, like knitting, and non-woven. The prepreg can be completely or only partially impregnated, for example, to facilitate the removal of air during curing.

[067] A preferred representative resinous matrix includes between about 22% w and 25% w Bisphenol-F diglycidyl ether; between about 25% w and 30% w triglycidyl-aminophenol (trifunctional epoxy resin); between about 17% w and 21% w diaminodiphenylsulfone (primarily 4,4-DDS as a curing agent); between about 10% w and 15% w insoluble particles of thermoplastics, and between about 13% w and 17% w poly (sulfone ether) as a hardening agent.

[068] The prepreg can be shaped using any of the standard techniques used to form composite parts. Typically, one or more layers of prepreg are placed in a suitable mold and cured to form the final composite part. The prepreg of the invention can be completely or partially cured using any temperature, pressure and time conditions known in the art. Typically, it will be cured in an autoclave at temperatures around 180 ° C. The composite material can most preferably be cured using a selected method of UV-visible radiation, microwave radiation, electron beam, gamma radiation, or other suitable thermal or non-thermal radiation.

[069] The composite parts produced from the improved prepreg of the present invention will find application in the production of articles such as numerous primary and secondary structures for use in the aerospace industry (wings, fusePetition 870180031805, from 04/19/2018, page 29 / 42

21/28 walls, brick walls, and the like), but it will also be useful in many other high-performance composite applications including automotive, rail and marine applications where high tensile strength, compressive strength, and resistance to impact damage.

[070] In order that the present invention may be more readily understood, reference will now be made below to background information and examples of the invention.

EXAMPLE 1 [071] A preferred representative formulation of resin according to the present invention is shown in TABLE 1. A matrix resin was prepared by mixing the epoxy ingredients at room temperature with the polyether sulfone to form a resinous mixture that was heated to 120 ° C. ° C for 120 minutes to completely dissolve the polyethersulfone. The mixture was cooled to 80 ° C and the rest of the ingredients added and mixed well.

TABLE 1

Quantity (% p) Ingredient 24.80 Bisphenol-F diglycidyl ether (GY281) 28.03 Trifunctional meta-glycidyl amine (MY0600) 18.66 Curative aromatic diamine (4,4-DDS) 15.00 Hardener (Sumikaexcel 5003P polyether sulfone) 13.50 Thermoplastic particles (Orgasol 1002 DNAT 1 nylon 6)

[072] The representative prepreg was prepared by impregnating one or more layers of the unidirectional carbon fibers with the resin formulation of TABLE 1. The unidirectional carbon fibers had a weight of 268 g / m ² and in all cases the resin matrix reached 35 percent by weight of the total weight of the uncured prepreg. A variety of prepreg layer layouts have been prepared using standard prepreg manufacturing procedures. The prepregs were cured in an autoclave at 180 ° C for about 2 hours. The cured prepregs were then subjected to standard tests to determine their resistance and tolerance to damage as described below.

[073] Shear strength (IPS) in plane and modulus (IPM) were

Petition 870180031805, of 04/19/2018, p. 30/42

22/28 determined at room temperature using a laminate of 8 thickness measures (+ 45 / -45). The laminate was cured for 2 hours at 180 ° C in an autoclave and produced a nominal thickness of 2 mm. Consolidation was verified by C-scan. The samples were cut and tested according to the Airbus AITM 1,0002 Test Method. The results presented are not normalized.

[074] Post-impact compression (CAI) was determined at 25 Joule using a 16-gauge thickness laminate in which the unidirectional fiber layers were oriented almost isotopically. The laminate was cured at 180 ° C for 2 hours in the autoclave. The final thickness of the laminate was about 4 mm. Consolidation was verified by C-scan. The samples were cut and tested using the Airbus AITM 1,0002 Test Method, published on June 2, 1994.

[075] The naked hole compression (OHC) was determined at room temperature using a 20-gauge thickness laminate in which the unidirectional layers were oriented in 40/40/20 during layering. The laminate was cured for 2 hours at 180 ° C in an autoclave and produced a nominal thickness of 5 mm. Consolidation was verified using a C-scan. The samples were cut and tested according to the Airbus AITM 1,0002 Test Method. The results are normalized values in the 60% volumetric fraction based on the nominal thickness of the cure thickness measure with the calculation performed as per EN 3784 method B.

[076] The bare hole tension (OHT) was determined at room temperature using a 20-gauge thickness laminate in which the unidirectional layers were oriented at 40/40/20 during layering. The laminate was cured for 2 hours at 180 ° C in an autoclave and produced a nominal thickness of 5 mm. Consolidation was verified using a C-scan. The samples were cut and tested according to the Airbus AITM 1,0008 Test Method. The results are normalized values in the 60% volumetric fraction based on the nominal thickness of the cure thickness measure with the calculation performed as per EN 3784 method B.

Petition 870180031805, of 04/19/2018, p. 31/42

23/28 [077] The cured prepreg had an IPS of about 101 MPa and an IPM of about 5.5 GPa. The OHT was about 780 MPa with the OHC and CAI being about 370 MPa and 292 MPa , respectively.

[078] A comparative prepreg (C1) was produced and tested in the same way as the preferred representative prepreg described above. C1 was identical to the representative prepreg except that the tri-functional para-glycidyl amine (MY0510) was replaced in place of the tri-functional meta-glycidyl amine (MY0600). The resulting cured prepreg had an IPS of about 72 MPa and an IPM of about 5.1 GPa. The OHT was about 752 MPa with OHC and CAI being about 361 MPa and 227 MPa, respectively.

[079] Comparative example C1 above demonstrates that an unexpected substantial increase in both tensile strength and damage tolerance occurs when trifunctional epoxy meta-glycidyl amine is used in place of trifunctional para-glycidyl amine epoxy. Additionally, this increase in both tensile strength and damage tolerance was achieved without adversely influencing the survival and grip of the prepreg or the other physical / chemical properties of the cured part.

[080] A second comparative prepreg (C2) was prepared in which the resinous matrix contained a combination of trifunctional para-glycidyl amine epoxy resin and tetrafunctional para-gricidyl amine epoxy resin. Specifically, the resin contained: 22.2% p difunctional epoxy GY281; 10.1% p MY0510 (tri-functional para-glycidyl amine epoxy); 21.1% p MY721 (tetrafunctional para-glycidyl amine epoxy); 13.5% for Orgasol 1002 particles; 14.0 Sumikaexcel 5003P PES; and 19.2% p 4,4'-DDS. The C2 prepreg was otherwise the same as the preferred representative prepreg and was cured and tested in the same way. The cured C2 prepreg had an IPS of about 92 MPa and an IPM of about 5.2 GPa. The OHT was about 735 MPa with the OHC and CAI being about 376 MPa and 257 MPa, respectively.

[081] Comparative example C2 demonstrates that replacing a substantial portion of the para-substituted tri-functional epoxy (MY0510) in C1 with a para-substituted tetrafunctional epoxy (MY721) provides some increase in most of the measured properties. However, the degree of increase was not even close

Petition 870180031805, of 04/19/2018, p. 32/42

24/28 as important as with the use of a meta-substituted tri-functional epoxy according to the present invention.

EXAMPLE 2 [082] Representative additional prepregs (A-D) were also prepared, cured and tested in the same manner as in Example 1. The prepregs were the same as in Example 1 except that the formulations for the matrix resins were changed. The formulations are shown in TABLE 2.

Table 2

Ingredient THE B Ç D 4,4’-DDS 9.33 22.40 11.20 7.01 3,3’-DDS 9.33 - 11.20 15.39 GY281 24.80 23.05 23.05 23.05 MY0600 28.03 26.05 26.05 26.05 Sumimkaexel 5003P 15.00 15.00 15.00 15.00 Orgasol 1002 13.50 13.50 13.50 13.50

[083] As can be seen from TABLE 2, matrix A resin is the same as in Example 1, except that the curing agent has been changed to a combination of 4,4'-DDS and 3,3'-DDS. For resin matrix B the amount of the curing agent was increased above that in Example 1 with a corresponding reduction in the components of the epoxy resin. For the C and D resins of the matrix, the amount of the curing agent was increased and combinations of 4,4'-DDS and 3,3'-DDS were used.

[084] Test results on prepreg cured using A-D resin matrices are shown in TABLE 3.

TABLE 3

THE B Ç D IPS (MPa) 97 106 103 92 IPM (GPa) 5.5 5.7 5.5 5.3 OHT (MPa) 797 820 823 825 OHC (MPa) 410 423 402 406 CAI (MPa) 277 295 286 270

[085] As can be seen from TABLE 3, the resistance and damage tolerance of cured prepregs varies when different amounts and types of curing agents are used. The totality of cured prepregs showed substantial increases in both tensile strength and damage tolerance when compared to Petition 870180031805, of 04/19/2018, p. 33/42

25/28 to the C1 prepreg of Example 1. It should be noted that the grip and survival properties of the prepreg produced according to this example varied, but were generally acceptable for typical handling, layering and curing processes. However, the prepreg grip and survival properties of Example 1 were more acceptable. Therefore, the amount of the curing agent and the combination (i.e. substantially all 4,4'-DDS and the like) used in Example 1 is preferred.

EXAMPLE 3 ^[086] An additional example (3E) of prepreg was produced according to the present invention. The prepreg included a carbon fiber reinforcement (weight 268 g / m ² ) that was similar to the carbon fiber used in the previous examples, except that a different fiber surface treatment was used. The formulation for the resin matrix is shown in TABLE 4. A comparative prepreg (C3) was also prepared. The matrix formulation for C3 is also shown in TABLE 4.

TABLE 4

% P ingredient C3 3E Araldite MY721 21.10 Araldite MY0510 10.10 Araldite MY0600 28.03 Araldite GY281 22.10 24.80 Sumikaexel 5003 14.00 15.00 Orqasol 1002N 13.50 13.50 4,4'-DDS 19.20 18.66

[087] Prepreg laminates were prepared and cured in the same manner as in the previous examples in order to conduct the standard mechanical tests presented above for OHT and CAI. The test results are shown in TABLE 5.

TABLE 5

C3 3E OHT (MPa) 594 677 FALLS 314 358

[088] The results of these examples demonstrate that the use of different fiber sealants or fiber coating treatments can result in variations in

Petition 870180031805, of 04/19/2018, p. 34/42

26/28 resistance and damage tolerance of the cured prepreg. For example, prepreg C3 was the same as prepreg C2, except for the use of a different coating on carbon fibers. CAI for C3 was 56 MPa higher than C2, but OHT for C3 was 141 MPa lower. The use of other surface coatings is also expected to possibly produce similar differences in the strength and damage tolerance of the cured prepreg when identical matrix resins are used.

[089] However, as also demonstrated by the Examples, the present invention provides a relative increase in resistance and damage tolerance to the cured prepreg, regardless of the particular coating or sealant being used. For example, the cured prepreg of Example 1 is the same as the cured prepreg of Example 3E, except for the use of a different coating on the carbon fibers. The cured prepreg of Example 1 had a CAI that was 35 MPa greater than that of C2 and an OHT that was 45 MPa greater. Likewise, the cured prepreg of Example 3E had a CAI that was 45 MPa greater than that of C3 and an OHT that was 83 MPa greater.

EXAMPLE 4 [090] Three additional examples of prepreg (FH) were produced according to the present invention. The prepreg included a carbon fiber reinforcement (weight 268 g / m ² ) which was the same as the fiber used in Example 3. The formulations for the three matrix resins are shown in TABLE 6.

TABLE 6

% P ingredient F G H Araldite MY721 10.00 Araldite MY0510 7.77 7.36 Araldite MY0600 20.00 18.96 25.00 Araldite GY281 24.55 23.27 16.54 Sumikaexel 5003 15.00 15.00 15.00 Orgasol 1002N 13.50 13.50 13.50 4,4'-DDS 19.18 21.91 19.96

[091] Representative F-H prepregs use low viscosity GY285 bisphenol-F instead of GY281, which is a moderate viscosity bisphenol-F epoxy. Additionally, F-H prepregs include mixtures of tri-functional epoxy metaPetição 870180031805, from 04/19/2018, p. 35/42

27/28 substituted (MY0600) and para-substituted polyfunctional epoxy (MY0510 and MY721). These prepregs were used to prepare laminates that were tested according to Boeing Test Methods on BMS 8-276 and demonstrated increased tensile strength and damage tolerance compared to similar laminates prepared from prepregs that did not contain meta-functional epoxy .

EXAMPLE 5 [092] Additional representative prepregs (I-M) were also prepared, cured and tested in the same manner as in Example 1. The prepregs were the same as in Example 1 except that the formulations for the matrix resins were changed. The formulations are shown in TABLE 6.

TABLE 6

Component (% p) I J K L M GY281 24.80 24.80 24.80 24.80 26.19 MY0600 28.03 28.03 28.03 28.03 29.60 PES 5003P 15.00 15.00 15.00 15.00 15.00 4,4-DDS 18.66 18.66 18.66 18.66 19.70 Orgasol 1002 DNAT1 6.75 6.75 4.75 Orgasol 3502 6.75 13.50 4.75 CG 199 Degree of growth 13.50 Orgasol 3801 DNAT1 6.75

[093] The cured prepregs were subjected to the same test procedures as in Example 1. The results are shown in TABLE 7.

Table 7

I J K L M IPS (MPa) 97 103/116 100.2 70 117 IPM (GPa) 4.9 5.0 / 5.0 4.6 4.3 4.9 OHT (MPa) - 817/831 814 1070 - OHC (MPa) 375 394/415 394 393 399 CAI (MPa) 326 296/340 308 243 333

[094] The representative prepregs above (I-M) demonstrate that various types and combinations of thermoplastic particles can be used according to the present invention to provide additional increases in both tensile strength and damage tolerance. It is evident that the use of Orgasol 3502 in combination with Orgasol 1002 (prepregs J and M) provides an increase in both the CAI and OHT of the cured prepreg when compared to the prepreg of the

Petition 870180031805, of 04/19/2018, p. 36/42

28/28

Example 1, which uses Orgasol 1002 alone. Additionally, the combination of Orgasol 3502 with Orgasol 1002 produces higher values of CAI and OHT than when Orgasol 3502 is used alone, as in prepreg K.

[095] Prepreg L shows that the use of Orgasol CG 199 in place of Orgasol 1002 had an unexpected effect on OHT. A high OHT value (1070) was recorded for the cured prepreg. However, the CAI value (243) was relatively low due to the lower particle molecular weight.

[096] According to the present invention, the amount of meta-substituted polyfunctional epoxy, together with other necessary ingredients, should be sufficient to provide cured prepreg that has an IPS of at least 70 MPa; and IPM of at least 4.6 GPa; OHC of at least 360 MPa; OHT of at least 790 MPa and CAI of at least 260 MPa as measured according to the standard test procedures presented in Example 1.

[097] Having thus described the representative modalities of the present invention, it should be noted by those usually skilled in the art that the disclosures presented are only representative and that several other alternatives, adaptations and modifications can be made within the scope of the present invention. Therefore, the present invention is not limited to the modalities described above, but is only limited by the claims presented below.

Petition 870180031805, of 04/19/2018, p. 37/42

1/4

Claims (20)

1. Pre-impregnated composite material, CHARACTERIZED by the fact that it comprises: A) reinforcement fibers; and B) a matrix comprising: a) a difunctional epoxy resin; b) a multifunctional aromatic epoxy resin with a functionality greater than two, said multifunctional aromatic epoxy resin having at least one phenyl group that is meta-substituted; c) insoluble thermoplastic particles; d) a thermoplastic curing agent; and e) a curing agent, in which “insoluble thermoplastic particles” means a thermoplastic material that is in a powder form, atomized form or particle form and that remains substantially in particulate form in the pre-impregnated resin matrix before curing, and where the prepreg is covered on both sides with a protective film. 2. Pre-impregnated composite material according to claim 1, CHARACTERIZED by the fact that the amount of said matrix in said pre-impregnated composite material is between 25 weight percent and 45 weight percent. 3. Pre-impregnated composite material, according to claim 1, CHARACTERIZED by the fact that said reinforcement fibers are selected from the group consisting of glass, carbon and aramid. 4. Pre-impregnated composite material according to claim 2, CHARACTERIZED by the fact that said reinforcement fibers are in the form of weaving fabric, unidirectional fibers, randomly oriented fibers or perforated quasi-isotropic unidirectional fiber tape. 5. Pre-impregnated composite material according to claim 1, Petition 870180031805, of 04/19/2018, p. 38/42 2/4 CHARACTERIZED by the fact that the said difunctional epoxy resin is selected from the group consisting of diglycidyl ether of bisphenol F, diglycidyl ether of bisphenol A, diglycidyl dihydroxy naphthalene and combinations thereof. 6. Pre-impregnated composite material, according to claim 1, CHARACTERIZED by the fact that said multifunctional aromatic epoxy resin is selected from the group consisting of triglycidyl meta-aminophenol and N, N, N ', N'- tetraglycidyl-m-xylenediamine. 7. Pre-impregnated composite material according to claim 1, CHARACTERIZED by the fact that said thermoplastic particles consist essentially of polyamide. 8. Pre-impregnated composite material, according to claim 1, CHARACTERIZED by the fact that said hardening agent is selected from the group consisting of polyether sulfone, polyether ether sulfone, polyphenyl sulfone, polysulfone, polyimide, polyetherimide, aramid , polyester, polyketone, polyetheretherketone, polyurethane, polyurea, polyarylether, polyarylsulfide, polycarbonate and polyphenylene oxide. 9. Pre-impregnated composite material according to claim 1, CHARACTERIZED by the fact that said curing agent is an aromatic amine. 10. Pre-impregnated composite material, according to claim 1, CHARACTERIZED by the fact that said matrix comprises: 22 to 28 weight percent of said difunctional epoxy resin; 25 to 30 weight percent of said multifunctional aromatic epoxy resin; 10 to 15 weight percent of said thermoplastic insoluble particles; 13 to 17 weight percent of said thermoplastic curing agent; and 15 to 17 weight percent of said curing agent. 11. Pre-impregnated composite material according to claim 10, CHARACTERIZED by the fact that said multifunctional epoxy resin is triglycidyl Petition 870180031805, of 04/19/2018, p. 39/42 3/4 meta-aminophenol. 12. Pre-impregnated composite material according to claim 11, CHARACTERIZED by the fact that said difunctional epoxy resin is bisphenol F diglycidyl ether. 13. Pre-impregnated composite material according to claim 12, CHARACTERIZED by the fact that said thermoplastic insoluble particles consist essentially of polyamide. 14. Pre-impregnated composite material according to claim 13, CHARACTERIZED by the fact that said thermoplastic hardening agent is polyether sulfone. 15. Pre-impregnated composite material according to claim 14, CHARACTERIZED by the fact that said curing agent is 4,4 diaminodiphenylsulfone. 16. Pre-impregnated composite material according to claim 13, CHARACTERIZED by the fact that said polyamide particles both comprise low melting polyamide particles having a melting temperature below the curing temperature of the pre-impregnated composite material and high-melting polyamide particles having a melting temperature above the curing temperature of the pre-impregnated composite material. 17. Pre-impregnated composite material, according to claim 15, CHARACTERIZED by the fact that said matrix comprises: 22 to 28 weight percent bisphenol F diglycidyl ether; 25 to 30 weight percent triglycidyl meta-aminophenol; 10 to 15 weight percent polyamide particles; 13 to 17 weight percent polyether sulfone; and 15 to 17 weight percent of 4,4-diaminodiphenylsulfone. 18. Part of the composite comprising a pre-impregnated composite material as defined in claim 1, CHARACTERIZED by the fact that said matrix has been cured. Petition 870180031805, of 04/19/2018, p. 40/42 4/4 19. Method for producing a pre-impregnated composite material, CHARACTERIZED by the fact that it comprises the steps of: A) provide a reinforcement fiber; and B) impregnating said reinforcement fiber with a matrix in which said matrix comprises: a) a difunctional epoxy resin; b) a multifunctional aromatic epoxy resin with a functionality greater than two, said multifunctional aromatic epoxy resin having at least one phenyl group that is meta-substituted; c) insoluble thermoplastic particles; d) a thermoplastic curing agent; and e) a curing agent; where "insoluble thermoplastic particles" means a thermoplastic material that is in a powder form, atomized form or particle form and that remains substantially in particulate form in the pre-impregnated resin matrix before curing, and in which the pre-impregnated it is covered on both sides with a protective film. 20. Method for producing a composite part, CHARACTERIZED by the fact that it comprises the step of curing a pre-impregnated composite material as defined in claim 1. Petition 870180031805, of 04/19/2018, p. 41/42